MY DISPLAY IS SHOWING THE BLUE VERTICAL LINES....

This is a issue with the display. In almost all cases, these lines are the result of a drop, or physical damage to the phone. Either way, you should take the phone to you nearest Apple Store with an appointment for the Genius Bar so they can evaluate the situation.

do you know the possible cost?

what would they do to the phone? Would they replace it ? Or would I have to get a new iPhone? I'm going to Genius Bar tomorrow afternoon about the vertical lines and about my sound problems after a drop